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GeSe: Optical Spectroscopy and Theoretical Study of a van der Waals Solar Absorber

Murgatroyd, PAE; Smiles, MJ; Savory, CN; Shalvey, TP; Swallow, JEN; Fleck, N; Robertson, CM; ... Veal, TD; + view all (2020) GeSe: Optical Spectroscopy and Theoretical Study of a van der Waals Solar Absorber. Chemistry of Materials , 32 (7) pp. 3245-3253. 10.1021/acs.chemmater.0c00453. Green open access

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Abstract

The van der Waals material GeSe is a potential solar absorber, but its optoelectronic properties are not yet fully understood. Here, through a combined theoretical and experimental approach, the optoelectronic and structural properties of GeSe are determined. A fundamental absorption onset of 1.30 eV is found at room temperature, close to the optimum value according to the Shockley–Queisser detailed balance limit, in contrast to previous reports of an indirect fundamental transition of 1.10 eV. The measured absorption spectra and first-principles joint density of states are mutually consistent, both exhibiting an additional distinct onset ∼0.3 eV above the fundamental absorption edge. The band gap values obtained from first-principles calculations converge, as the level of theory and corresponding computational cost increases, to 1.33 eV from the quasiparticle self-consistent GW method, including the solution to the Bethe–Salpeter equation. This agrees with the 0 K value determined from temperature-dependent optical absorption measurements. Relaxed structures based on hybrid functionals reveal a direct fundamental transition in contrast to previous reports. The optoelectronic properties of GeSe are resolved with the system described as a direct semiconductor with a 1.30 eV room temperature band gap. The high level of agreement between experiment and theory encourages the application of this computational methodology to other van der Waals materials.

Type: Article
Title: GeSe: Optical Spectroscopy and Theoretical Study of a van der Waals Solar Absorber
Open access status: An open access version is available from UCL Discovery
DOI: 10.1021/acs.chemmater.0c00453
Publisher version: https://doi.org/10.1021/acs.chemmater.0c00453
Language: English
Additional information: This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/10096940
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